A present invention relates to a processing chamber having a mounted chamber having a high-corrosion-resistant film and applied to a film forming apparatus, heat processing apparatus and etching apparatus as used in a CVD (Chemical Vapor Deposition), etc.
In response to a recent demand for a high density and high integration unit, a semiconductor device is progressed from a two-dimensional connection structure toward a three-dimensional multi-connection structure. For this reason, the burying technique for electrical interlayer connection using a contact hole for connection between an underlying circuit element and an overlying connection layer and a via hole for connection between an underlying connection layer and an overlying connection layer, and so on, is becoming important. For the burying of the contact hole and via hole, use is made of Al (aluminum), W (tungsten) or an alloy including these as a main component.
At the burying step using aluminum or aluminum alloy, a heating step and so on are involved during a manufacture. If the aluminum connection line and underlying silicon (Si) substrate are directly contacted with each other, there is a risk that there will occur a “Si-sucking-up” effect of aluminum, etc., at its boundary area and an alloy will be newly formed there. The alloy thus formed is greater in the value of a resistance and is not desirable from the standpoint of a power saving and high-speed operation demanded of a resultant device. Further, when tungsten or tungsten alloy is used as a burying layer in the contact hole, WF6 gas intrudes into the silicon substrate, thus offering a possibility of deteriorating the electrical characteristic, etc., of the device. This is, therefore, not preferable.
In order to prevent the occurrence of such a problem, a barrier layer is formed on the bottom and inner wall of the hole before forming a buried layer in the contact hole or via hole and then such a buried layer is formed. Generally, a TiN film is known as a barrier layer.
With a trend toward the high-density integration, on the other hand, a high dielectric constant material such as Ta2O5 is used as a capacitor gate material to obtain a higher capacitance without changing its scale. However, such a higher dielectric constant material is not stabler in characteristic than SiO2 conventionally used as the capacitor gate material. If a poly-Si is used on the overlying electrode, it is oxidized due to the chemical reaction after the formation of the capacitance, thus failing to manufacture a device element of stable characteristics. It is, therefore, necessary that a less-oxidized TiN film be used as an overlying electrode.
The TiN film has been formed by using a physical vapor deposition (PVD) technique and a demand has been made for a finer and higher integration device in particular. In addition, the design rules are particularly stringent. Hence, in PVD that can hardly achieve high coverage. Therefore, a chemical vapor deposition (CVD) technique is used by which it is possible to form a TiN film of a better quality. Stated in more detail, a thermal CVD is used, in which TiCl4 and NH3 (ammonia) or MMH (monomethylhydrazine) is applied, as a reaction gas, to a heated substrate. In the case where the TiN film is formed by such a thermal CVD, chlorine is liable to be retained in a formed film, thus presenting a problem. The retaining of such chlorine results in a higher specific resistance and it is not possible to obtain a proper characteristic if the film is applied to an electrode overlying a capacitor.
Further, the TiN film, being a columnar crystal, is liable to be boundary-diffused and involves a lower barrier characteristic. The lower barrier characteristic presents a problem in the case where the TiN film is used as a barrier layer for a Cu connection line or an oxygen diffusion barrier for Ta2O5 connection line of an electrode overlying the capacitor. That is, a problem occurs due to the corrosion of the Cu connection line by the residual chlorine or a lowering of a capacitance of Ta2O5 by the diffusion of oxygen.
An amount of Cl in the formed film can be indeed reduced by making a film formation temperature higher. However, a high temperature process is not preferable due to a problem, such as thermal resistance and the corrosion, of a connection line material such as Cu and Al.
As one technique of plasma CVD, there is an ICP (Inductively Coupled Plasma)—CVD according to which an antenna member such as a coil is provided around a bell jar (chamber). By applying a high frequency power to it, an inductive electromagnetic field is created to provide plasma. In the case where the TiN film is formed using this technique, the formed TiN film becomes low-resistance and low in chlorine, and even a film formed at a relatively low temperature is made low in an amount of residual chlorine.
Although a chamber made of quartz or alumina is used in the formation of the TiN film by the ICP-CVD, it is not good in a plasma-resistant characteristic and a corrosion resistance to an etching gas such as ClF3 used for cleaning the interior of the apparatus after the formation of the TiN film is not better, thus presenting a problem.
Further, in this type of CVD film formation apparatus, a deposit is formed on the inner wall of the chamber due to the introduction of a process gas from above the chamber and a foreign deposit is liable to be formed. In the case of forming the TiN film, the plasma created is attenuated due to the deposit of a conductive film on the inner wall of the upper chamber, thus making it difficult to form a film.